Author: Scott

ScrollViewer+ItemsControl vs. ListView

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One of my most recent tasks at work was determining the cause of slow performance in one part of an application and coming up with a fix (if possible).  We tracked the source of the problem down to a use of ItemsControl inside a ScrollViewer.  Because the ItemsControl instance was trying to display hundreds of complex items, it took a noticeably long time to load.  This turns out to be a known issue, with a few possible solutions.  Simply changing the ItemsPanelTemplate of the ItemsControl instance to contain a VirtualizingStackPanel didn’t fix our performance problem.

What did resolve our performance issue was replacing the ScrollViewer and ItemsControl combination with a ListView.  The list of what we changed includes:

  • Giving the ListView the same name as the ItemsControl.
  • Giving the ListView the same ItemsSource as the ItemsControl.
  • Update the ItemsPanelTemplate of the ListView to use VirtualizingStackPanel.
  • Set HorizontalScrollBarVisibility to “Disabled”.
  • Bound the Visibility property of the ListView to a Converter.
  • Update the ItemContainerStyle with a ListViewItem style that sets the HighlightBrushKey and ControlBrushKey to be transparent.

Note: The last of those steps does override those styles for the entire application, so it may be best to skip it unless it doesn’t negatively impact the look-and-feel of the rest of your application.

The changes we made reduced the load time from around 20 seconds down to less than 2 seconds for 400 items.

The tradeoff in moving to a ListView (with VirtualizingStackPanel) from ScrollViewer+ItemsControl is scrolling speed.  Scrolling through 400 items does go more slowly, but it’s preferable to waiting as long as we did just to see the data.

Bloatware happens when you aren’t the only customer

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This article in Ars Technica reminded me of one of the things I never liked about PCs you bought from Dell, HP, or any major vendor–bloatware.  Every PC I’ve had that I didn’t build myself, and every Windows laptop had multiple pieces of software that I didn’t want.  The least-offensive of these apps merely took up hard drive space.  The worst made the computer slower and more of a hassle to use.  Switching from Windows to Mac at home meant no more bloatware.  Moving to an Intel chip-based Mac extended the no-bloatware experience to Windows VMs.  Moving to the iPhone a couple of years ago (and sticking with it by buying an iPhone 4) seems to have spared me from vendor bloatware as well.  This is especially important in the mobile space because today’s smartphones have a lot less storage space to waste, and less-powerful CPUs than modern PCs.

Bloatware happens on the PC because even though we buy them, we aren’t the only customer.  Every company with some anti-virus software to sell, a search engine they want you to use, or some utility they want you to buy wants to be on your PC or laptop.  They’re willing to pay to be on your new machine, and PC vendors aren’t going to turn down that money.  A similar thing seems to be happening on Android phones now.  Here’s the key quote from the story:

“It’s different from phone to phone and operator to operator,” says Keith Nowak, spokesman for HTC. “But in general, the apps are put there to meet the operator’s business and revenue needs.” (emphasis mine)

The money we pay for our voice and data plans isn’t the only money that Verizon, AT&T, Sprint, & T-Mobile want.  Some of these carriers have decided that they’ll take money from other companies who want to put applications on the smart-phones they sell.  This highlights one of the key differences between the way Google approaches the mobile phone market and the way Apple does it.

When it comes to Android, you and I aren’t Google’s customers–not really.  The real customers are mobile phone hardware vendors like Motorola and HTC.  They need to care how open and customizable Android is because they expect it to help them sell more phones.  Making the OS free for the vendors is in Google’s interest because the bulk of their revenue comes from advertising.  The more phones there are running Android, the more places their ads will appear.  Android’s openness is only of interest to us as users to the extent it allows us to do what we want with our mobile phone.

Unlike Google, Apple is in business to sell us electronics.  They expect iOS4 to help them sell more iPhones and iPads.  But since you and I are the customers Apple is chasing, no pre-loading of apps from third parties.  It doesn’t mean they won’t feature apps that highlight the phone’s capabilities (Apple does plenty of that).  Nor does it mean we can’t get apps from AT&T, just that putting them on and taking them off is our choice.  There is a tradeoff as far as how long iPhone users wait for features when compared with Android phone users.  But I think the iPhone features all work better, and work together to create arguably the best smartphone available.

My First PowerShell Cmdlet

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We’ve been using PowerShell to write automated tests of the UI on my current project.  One of the tasks I took on today was creating a custom cmdlet to enable us to select radio buttons.

I already had an existing assembly of cmdlets to work with, so I just added a new class (SelectRadioButton) to it.  Next, I added references to System.Management.Automation and System.Windows.Automation. With these references in place, I could add this attribute to the class:

[Cmdlet(VerbsCommon.Select, "RadioButton", SupportsShouldProcess = true)]

The attribute determines the actual name of the cmdlet you’ll use in scripts (Select-Radiobutton).  The cmdlet needs an instance of AutomationElement to operate on, so that’s defined next:

[Parameter(Position = 0, Mandatory = true, HelpMessage = "Element containing a radio button control")]
[ValidateNotNull]
public AutomationElement Element { get; set;}

Finally, I adapted some of the logic for my override of the ProcessRecord from this article on using UI automation.  The end result looks something like this:

protected override void ProcessRecord()
{
try
{
if (Element.Current.ControlType.Equals(ControlType.RadioButton))
{
SelectionItemPattern pattern = Element.GetCurrentPattern(SelectionItemPattern.Patern) as SelectionItemPattern;
if (pattern != null) pattern.Select();
}
else
{
//Put something in here for handling something other than a RadioButton
}
}
catch (Exception ex)
{
// You could put some logging here
throw;
}
}

In non-iPhone 4 news

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Apple stealthily revised the Mac mini.  Get the full story here, but the part I think is the most interesting is that they designed in a removable panel on the bottom to make it easy to replace the RAM yourself.  It shows a rare bit of flexibility from Apple when it comes to their hardware.

As for the rest of the device:

  • No more power brick?  Nice!
  • Tons of ports (including HDMI).
  • SD card slot
  • No Blu-Ray?  Rats.  “Bag of hurt” or no, that would have been nice.
  • The price bump from the previous version of the Mac mini seems a bit steep.

The original Mac mini was the first computer I ever bought from Apple.

When default settings attack

Posted on by Scott

When you first install SQL Server 2008 Express, the TCP/IP protocol is disabled by default.  Be sure the protocol is enabled (which requires restarting the service) before you try to run an application that depends on it, otherwise you could spend hours trying to figure out why your application won’t work.  It looks like SQL Server 2008 R2 Developer behaves the same way.

I suggested this awhile back to a co-worker who’d been struggling all day with why an application wasn’t working, and it turned out to be the solution.

To Curacao and back

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I spent the past 7 days vacationing in Curacao with my girlfriend Ebony and another couple we’re friends with.  In this post, I’ll talk about how it went, and how I might have done things differently if I were visiting again.

Why Curacao?

Ebony has wanted to go there for awhile, because of the beautiful water, sun, and beaches.

What to wear

Definitely wear light clothing.  Average high temperatures in Curacao are mid-to-upper 80s Fahrenheit year-round.  Don’t skimp on sunscreen, or you’ll regret it–even if your skin is already relatively dark.  My friends aren’t that much lighter than me, and all of them got burnt.  Don’t go easy on bug spray either.

Accommodations

We spent two nights at Renaissance Curacao Resort & Casino in Willemstad.  If you’re familiar with and/or a fan of Marriott properties, this one has everything you expect.  They also have plenty of outlets for appliances and electronics from the U.S., so you won’t need to use converters.  The only wi-fi access appeared to be in the lobby, and I never managed to connect with my iPhone.  There’s wired internet access from the rooms, so netbook and laptop users will have an alternative to the business center.  The private beach they talk about on their web page is man-made, and doesn’t connect directly to the ocean, but a large saltwater pool.

We spent the rest of the time at the Hyatt Regency Curacao Golf Resort, Spa, and Marina.  Parts of the property are still under construction, so we got the benefit of a grand opening rate, 4 nights for the price of 3, and free breakfast for the duration of our stay.  The service we received from every member of the staff was excellent.  Without exception, they were all incredibly courteous and polite, and went out of their way to accommodate our requests.  I thought the rooms were nice, but some of the balconies are much better for privacy than others.  The tub has a rather high edge, so it’s a bit of a challenge to get into unless you’re tall.  Strangely, the shower only has frosted glass on half the length of the tub–and no sliding door.

Food

Bistro Le Clochard was expensive, but the food was excellent.  It’s inside Rif Fort, a very short walk from the Renaissance.  We discovered that their kitchen accommodates vegetarians quite well.  It seems to be a quite popular place, so make reservations ahead of time, or you’ll have to eat elsewhere.  The restaurant within the Renaissance is ok.

The Hyatt has three restaurants: Medi, Shor, and Swim.  The food at all of them is quite good, though the serving times vary widely (Shor is the slowest, Swim is the fastest).  Swim will serve you poolside or at the beach.  Their plantain chips and fish tacos were especially good.

How to pay

U.S. currency was accepted everywhere we tried to use it, as were our credit cards.  I checked the tourist board website to get information ahead of time.

Activities, Attractions, & Shopping

Of the attractions available in Curacao, we got to the Kura Hulanda Museum and the Rif Fort in Willemstad.  At Kura Hulanda, the extra money for a tour guide was well worth it.  It provides a great history lesson of many cultures, as well as the slave trade.  With more time, I would have visited the Mikve Israel-Emanuel Synagogue and the Maritime Museum as well.

During our time at the Hyatt, we went on a 3-hour cruise with some time for snorkeling.  I still regret my lack of underwater camera gear for this, because there were a lot of strange and beautiful fish to see.  There was even a small shipwreck close to where we snorkeled that we were able to see.  Ocean Encounters handled our tour, and they did an excellent job.  If we’d planned further in advance, we could have gone on the 7-hour cruise to and from Klein Curacao.  This trip made me wish I knew how to scuba dive.  A trip back for the sole purpose of getting PADI-certified would probably be worth it.

At least in Willemstad, there are tons of places to buy jewelry, electronics, clothes, and souvenirs.  Prices in downtown were pretty good from what I saw.  The street vendors just outside the Rif Fort offered the best prices, and we ended up getting a couple of very nice things in both places.

Getting there (and back)

We flew American Airlines from Reagan National Airport to Hato International via Miami.  Our friends flew to Miami from Philadelphia, then to Hato International.  During the time I researched flight costs, they ranged from $450/person to well over $600/person.  We ended up using frequent flier miles for the DCA-MIA leg of the trip to cut down our out-of-pocket costs.  If I had it to do over again, I’d have planned much further in advance.

One thing I noticed (to my annoyance) about flying into and out of Miami is that the gate personnel decided to pick on either Ebony or both of us about the size of our carry-on luggage.  To make sure you avoid that kind of harassment, make sure your packed carry-on fits in the stupid little cages they have near the gates.  Otherwise, you could end up having to check a bag you weren’t expecting and risk the airline losing it (like American Airlines nearly did with her bag).

The last thing I’ll say about flying to and from Curacao (at least in this post), is to avoid taking the last flight out of Curacao on whatever day you depart.  If there’s a problem with that flight (as there was in our case), you’ll be stuck at least one extra day.

Going beyond files with ItemGroup

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If you Google for information on the ItemGroup element of MSBuild, most of the top search results will discuss its use in dealing with files.  The ItemGroup element is far more flexible than this, as I figured out today when making changes to an MSBuild script for creating databases.

My goal was to simplify the targets I was using to create local groups and add users to them.  I started with an example on pages 51-52 of Inside the Microsoft Build Engine: Using MSBuild and Team Foundation Build, where the author uses an ItemGroup to create a list of 4 servers.  Each server has custom metadata associated with it.  In his PrintInfo target, he displays the data, overrides an element with new data, and even removes an element.  Because MSBuild supports batching, you can declare a task and attributes once and still execute it multiple times.  Here’s how I leveraged this capability:

  1. I created a target that stored the username of the logged-in user in a property.
  2. I created an ItemGroup.  The metadata for each group element was the name of the local group I wanted to create.
  3. I wrote the Exec commands to execute on each member of the ItemGroup

The ItemGroup looks something like this:

<ItemGroup>
<LocalGroup Include=”Group1″>
<Name>localgroup1</Name>
</LocalGroup>
<LocalGroup Include=”Group2″>
<Name>localgroup2</Name>
</LocalGroup>
<LocalGroup Include=”Group3″>
<Name>localgroup3</Name>
</LocalGroup>
</ItemGroup>

The Exec commands for deleting a local group if it exists, creating a local group, and adding the logged-in user to it, look like this:

<Exec Command=”net localgroup %(LocalGroup.Name) /delete” IgnoreExitCode=”true” />
<Exec Command=”net localgroup %(LocalGroup.Name) /add” IgnoreExitCode=”true” />
<Exec Command=”net localgroup %(LocalGroup.Name) $(LoggedInUser) /add” />

The result is that these commands are executed for each member of the ItemGroup.  This implementation makes a lot easier to add more local groups if necessary, or make other changes to the target.

From enthusiast to user

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My friend Sandro read this Slate piece yesterday and wrote this blog entry in part about enthusiasts and users.  I think his concern that today’s computer science students seem to be more users than enthusiasts is very legitimate, since they’re some of the people we’re counting on for the next advances in the field of computing and innovative new products.  The similarity he sees between advances in automobiles and computing is an interesting one.  I agree with him up to a point about commoditization, but I see real benefits to certain things becoming commodities.  He touches only briefly on case mods in the PC space, but commodity hardware (RAM, hard drives, video cards, etc) has made it a lot easier for the technically-inclined to build entire PCs themselves, instead of buying whatever Dell or HP is selling this week.  Commodity hardware and operating systems are what enable a product like TiVo to exist (along with less-capable imitators).  We have commodity hardware to thank for the XBox 360, and commodity operating systems to thank for XBMC.  This doesn’t mean that a ton of people will avail themselves of the option to build their own PC, or their own home theater PC, just that the option is definitely out there for those who want to.

I suspect it has always been the case that the vast majority of people would rather use something cool than build it.  As much as those of us in the U.S. love cars, very few of us will be building our own Rally Fighter anytime soon.  I enjoy photography as a hobby, but I haven’t been in a darkroom to develop my own film in years (nor did I ever spend enough time in one to get really good at the process).  At least with computers, there came a point for me where fiddling around inside the guts of a computer to get something working again got to be too much of a hassle.  This could mean I’m gotten lazy, but I really like it when things just work.  There’s definitely something to be said for having the ability to fix something or hack it to do something beyond its original purpose.  I’ve always admired people like that, and I think they’re responsible for a lot of the great advances we benefit from today.

I think human nature is such that we won’t run out of enthusiasts anytime soon.  As long as there are magazines like MAKE and sites like iFixit, enthusiasts will continue to do things that make users jealous.

Adventures in e-commerce

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I’m working on an e-commerce site for the first time in about 10 years.  The site is Trés Spa, a skin care products company in northern California.  Unlike my previous forays into e-commerce, none of the technologies I’m using come from Microsoft.  I’m using the community edition of Magento.  So far, I’ve been able to update the configuration so that USPS shipping options show up in shipping and tax estimates.  I haven’t had to write any code yet, but we’ll see if that changes.  Despite running WordPress for awhile, I’ve done very little with PHP.